1. Field of the Invention
The present invention relates to an actuator and a lens unit and camera equipped therewith, and more particularly to an actuator and a lens unit and camera equipped therewith in which imaging lenses are moved within a plane perpendicular to the optical axis thereof to prevent image blurring.
2. Description of Related Art Including Information Disclosed Under 37 CFR §§1.97 and 1.98
JP 2001-290184 (Patent Document 1) describes an observation device. In this observation device a movable piece, to which a blur compensation lens is attached, is supported by three balls (spherical bodies), and image blurring is compensated by moving the blur compensation lens within a plane perpendicular to the optical axis. The balls supporting the movable piece are disposed inside a square limiting portion (walls). Furthermore, the observation device translationally moves the movable piece up to a maximum degree of movement, causing each ball to contact a limiting portion, after which a reset operation is performed to return the movable piece by a predetermined distance. Each ball is positioned by this reset operation within a certain range which is returned by a predetermined distance from the position at which contact was made with a limiting piece.
JP 2006-119249 (Patent Document 2) describes an actuator used to prevent image blurring. In this actuator, a moving frame is caused to rotate around an optical axis up to a locking position, and the moving frame is locked by engagement between a protuberance formed on the periphery of the moving frame and a cam-shaped piece disposed corresponding thereto.
The actuator described in JP 2006-119249 has the advantage that the moving frame can be locked without providing a special actuator for the purpose of locking the moving frame.    Patent Document 1: JP 2001-290184    Patent Document 2: JP 2006-119249
3. Problems to Be Solved by the Invention
However, in the observation device described in JP 2001-290184, the movable piece to which the blur compensation lens is attached is caused to move translationally to the maximum degree of movement during the reset operation, causing the problem that images formed during the reset operation are significantly blurred.
A further problem arises because in the observation device a special reset operation must be executed in order to position the balls (spherical bodies) within a certain range; therefore the observation device cannot be used during the period of the reset operation.
The actuator described in JP 2006-119249 has a further problem in that the protuberance for locking the moving frame (movable portion) and the cam-shaped piece used to engage therewith must be disposed on the outer perimeter of the moving frame, thereby increasing the outside diameter of the actuator.
Also, in the actuator the steel balls (spherical bodies) which lock the moving frame are not themselves locked even when the moving frame (movable portion) is locked, therefore when a shock force acts on a locked moving frame, there is a risk that the steel balls will fall out.
Furthermore, because in the actuator the steel balls are not positioned even when the moving frame (movable portion) is locked, it is difficult to reliably position the steel balls to an appropriate location when recovered to image blur prevention control.